(1) Field of the Invention
The present invention relates to a radio system, and more particularly, to a resource management system for RAN (Radio Access Network) which is built by an IP (Internet Protocol) network.
(2) Description of the Related Art
RAN is basically comprised of a node B which is a radio base station device, and RNC (Radio Network Controller) which is a radio control apparatus. The node B is connected to UE (User Equipment) which is a mobile device through a radio interface. The RNC performs management of radio resources, control of node B, CAC (Connection Admission Control) process, handover control and the like. An lub interface is defined as an interface between the node B and RNC, while an lur interface is defined as an interface between RNCs.
In RAN which is built by an ATM (Asynchronous Transfer Mode) network, a clay pipe is built using ATM transport for transferring user data. TB (Transport Block) is used for transferring user data.
In the RAN described above, negotiations are made between nodes in order to establish and release a resource number (AAL2 Path ID, CID) for the clay pipe (TB) by a protocol called ALCAP. A resource in network is managed by performing the negotiations.
In the following, a description will be given of resource management in the ATM transport. Here, assume, as RNC, that SRNC (Serving RNC) and DRNC (Drift RNC) are installed.
FIG. 1 shows a resource management procedure upon resource capturing. Referring to FIG. 1, SRNC first transmits an RNSAP message “Radio Setup Request” to DRNC, and DRNC which has received the message transmits an NBAP message “Radio Setup Request” to node B. In response to the NBAP message from DRNC, node B transmits an NBAP message “Radio Setup Response” to DRNC. Upon receipt of the response message from node B, DRNC transmits an RNSAP message “Radio Setup Response” to SRNC. In this way, a radio link setup (connection setup) is performed by passing the RNSAP message and NBAP message among respective nodes such as SRNC, DRNC, and node B.
After setting up the radio link, resource allocation and CAC are performed in each of the lur and lub interfaces by transmitting and receiving ALCAP-based messages among the respective nodes SRNC, DRNC, and node B. CAC is software control for determining whether or not a connection setup can be admitted. CAC rejects the admission of a call if the quality of communication cannot be guaranteed due to a lack of network resources, taking into consideration the band and required QoS (Quality of Service) conditions, in order to ensure communication quality.
With lur, an ERQ (Establish Request) message is passed from SRNC to DRNC. The ERQ message includes parameters such as “Peak CPS SDU Bit rate,” “Peak CPS SDU Size,” “Average CPS SDU Bit rate,” “Average CPS SDU size,” “AAL2 path ID (VPCI+VCI),” “CID,” and the like. Here, parameters related to resources are “AAL2 path ID” and “CID,” and resources are allocated using these parameters.
In regard to CAC, the value of [band of previously assigned resources]+[Average CPS SDU Bit rate/Average CPS SDU size] is calculated using parameters “Average CPU SDU Bit rate” and “Average CPS SDU size,” and the calculation result is compared with an allowance for a band of VCI. When the calculation result is equal to or smaller than the allowance, the admission of resources is permitted, whereas when the calculation result exceeds the allowance, the admission of resources is rejected.
Likewise, with lub, the ERQ message is passed between DRNC and nodes, and the allocation of resources and CAC are performed using parameters included in the ERQ message in a manner similar to lur.
FIG. 2 shows a resource management procedure when resources are released. Referring to FIG. 2, SRNC first transmits an RNSAP message “Radio Reconfiguration Prepare” to DRNC, and DRNC, which has received the message, transmits an NBAP message “Radio Reconfiguration Ready” to node B. Upon receipt of the message from DRNC, node B transmits an NAP message “Radio Configuration Ready” to DRNC. Upon receipt of the message from node B, DRNC transmits an RNSAP message “Radio Reconfiguration Response” to SRNC.
Upon receipt of the response message from DRNC, SRNC transmits an RRC message “Radio Bearer Release Request” to node B. Subsequently, ALCAP-based REL (Release Request message) and RLC (Release Complete message) are passed among the respective nodes, SRNC, DRNC, and node B to releases and to update a CAC band accumulated value in each of the lur and lub interfaces.
In order to determine whether or not a band value declared by the user upon Bear establishment is a band which can be processed by an ATM transport, the band value declared by the new user upon Bear establishment is added to the total value of previously established users' Bear bands, and the sum is compared with the capacity of the ATM transport (physical pipe diameter). The addition of a band value declared by a new user to the total value of previously established users' Bear bands is called “CAC band accumulation.” The CAC band accumulated value is given by [Σ (previously established per-user Bear band value)+(Bear band value newly established this time)].
Incidentally, a next-generation network employs RAN which is built by an IP (Internet Protocol) network. In this IP-based RAN, a resource management method has been proposed on assumption of IP services.
JP-2006-279923-A discloses a method of managing one or a plurality of IP-based resources in a packet-based access network. In this resource management method, at least one IP-based resource is validated for a particular user from among a first wireless connection through a first interface and a second wireless connection which becomes active at the same time through a second interface. Next, during a particular service for a particular user, information indicative of transmission of a plurality of packets is delivered through the first and second wireless connections and wired line connections. Then, based on associated information, at least one connection is selected from among the first and second wireless connections and wired line connections, to determine routing of the plurality of packets in the packet-based access network.
However, the foregoing related art has the following problems.
Since no special protocol exists for establishing TB, such as ALCAP, in the IP-based RAN, the resource management cannot be applied in ALCAP as shown in FIGS. 1 and 2.
The IP-based resource management method described in JP-2006-279923 assumes IP services in an IP network which terminates at UE and HA (Home agent) and is intended for processes on a user data layer. Accordingly, this resource management method would encounter difficulties when applied to resource management in IP transport at the RNC level.
Thus, the resource management in the IP transport at RNC level has not so far been realized in the IP-based RAN.